Nicholas R. Eaton

An invariant dimensional liability model of gender differences in mental disorder prevalence: evidence from a national sample.

Epidemiological studies of categorical mental disorders consistently report that gender differences exist in many disorder prevalence rates and that disorders are often comorbid. Can a dimensional multivariate liability model be developed to clarify how gender impacts diverse, comorbid mental disorders? We pursued this possibility in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; N = 43,093). Gender differences in prevalence were systematic such that women showed higher rates of mood and anxiety disorders, and men showed higher rates of antisocial personality and substance use disorders. We next investigated patterns of disorder comorbidity and found that a dimensional internalizing-externalizing liability model fit the data well, where internalizing is characterized by mood and anxiety disorders, and externalizing is characterized by antisocial personality and substance use disorders. This model was gender invariant, indicating that observed gender differences in prevalence rates originate from women and mens different average standings on latent internalizing and externalizing liability dimensions. As hypothesized, women showed a higher mean level of internalizing, while men showed a higher mean level of externalizing. We discuss implications of these findings for understanding gender differences in psychopathology and for classification and intervention.

Deriving an empirical structure of personality pathology for DSM-5.

The DSM-IV model of personality disorders is composed of trait sets arranged into 10 theoretically distinct, polythetically assessed categories, with little regard for how the traits comprising these disorders are interrelated and structured. Research since the publication of DSM-III has shown that this model is untenable. The question is not whether this model needs revision; rather, the question is how to move from the existing DSM-IV framework to a model better connected with data. Empirically-based models of personality trait variation provide a starting point for DSM-5, and ongoing research will be used to delineate further the empirical structure of personality traits in the pathological range. The ultimate goal is to frame future DSMs in a way that is maximally useful for clinicians as well as researchers. It is also critical to understand that the DSM-5 is intended to be a living document that will facilitate novel inquiry and clinical applications, as opposed to a document designed to promote and perpetuate a fixed set of constructs. Thus, we view a proposed trait system as a first step on a path to a well-validated, clinically-useful structure.

The structure of psychopathology: Toward an expanded quantitative empirical model

There has been substantial recent interest in the development of a quantitative, empirically based model of psychopathology. However, the majority of pertinent research has focused on analyses of diagnoses, as described in current official nosologies. This is a significant limitation because existing diagnostic categories are often heterogeneous. In the current research, we aimed to redress this limitation of the existing literature, and to directly compare the fit of categorical, continuous, and hybrid (i.e., combined categorical and continuous) models of syndromes derived from indicators more fine-grained than diagnoses. We analyzed data from a large representative epidemiologic sample (the 2007 Australian National Survey of Mental Health and Wellbeing; N = 8,841). Continuous models provided the best fit for each syndrome we observed (distress, obsessive compulsivity, fear, alcohol problems, drug problems, and psychotic experiences). In addition, the best fitting higher-order model of these syndromes grouped them into three broad spectra: Internalizing, Externalizing, and Psychotic Experiences. We discuss these results in terms of future efforts to refine emerging empirically based, dimensional-spectrum model of psychopathology, and to use the model to frame psychopathology research more broadly.

The Hierarchical Taxonomy of Psychopathology (HiTOP) : A Dimensional Alternative to Traditional Nosologies

The reliability and validity of traditional taxonomies are limited by arbitrary boundaries between psychopathology and normality, often unclear boundaries between disorders, frequent disorder co-occurrence, heterogeneity within disorders, and diagnostic instability. These taxonomies went beyond evidence available on the structure of psychopathology and were shaped by a variety of other considerations, which may explain the aforementioned shortcomings. The Hierarchical Taxonomy Of Psychopathology (HiTOP) model has emerged as a research effort to address these problems. It constructs psychopathological syndromes and their components/subtypes based on the observed covariation of symptoms, grouping related symptoms together and thus reducing heterogeneity. It also combines co-occurring syndromes into spectra, thereby mapping out comorbidity. Moreover, it characterizes these phenomena dimensionally, which addresses boundary problems and diagnostic instability. Here, we review the development of the HiTOP and the relevant evidence. The new classification already covers most forms of psychopathology. Dimensional measures have been developed to assess many of the identified components, syndromes, and spectra. Several domains of this model are ready for clinical and research applications. The HiTOP promises to improve research and clinical practice by addressing the aforementioned shortcomings of traditional nosologies. It also provides an effective way to summarize and convey information on risk factors, etiology, pathophysiology, phenomenology, illness course, and treatment response. This can greatly improve the utility of the diagnosis of mental disorders. The new classification remains a work in progress. However, it is developing rapidly and is poised to advance mental health research and care significantly as the relevant science matures.

Personality traits and the classification of mental disorders: Toward a more complete integration in DSM-5 and an empirical model of psychopathology

Personality trait dimensions are related to a wide variety of important life outcomes, such as mortality, physical and mental health, and interpersonal relationships. Nevertheless, the diagnostic system with arguably the most influence in mental health settings (Diagnostic and Statistical Manual of Mental Disorders, 4th ed. [DSM-IV]) formally includes personality primarily in the form of 10 putatively categorical personality disorders. We advocate a more complete and extensive integration of personality in future DSMs, via the explicit inclusion of an empirically based, dimensional personality trait model. To justify this position, we provide a broad review of the ways in which personality traits have proven useful in the description and conceptualization of personality disorders and other mental disorders, as well as in the prediction of key clinical phenomena. We also discuss the importance of constructing a comprehensive quantitative model of psychopathology based on data, an endeavor that is motivated and informed by the close conceptual and empirical parallels between personality and psychopathology.

Borderline personality disorder co-morbidity: relationship to the internalizing-externalizing structure of common mental disorders.

BACKGROUND Borderline personality disorder (BPD) shows high levels of co-morbidity with an array of psychiatric disorders. The meaning and causes of this co-morbidity are not fully understood. Our objective was to investigate and clarify the complex co-morbidity of BPD by integrating it into the structure of common mental disorders. METHOD We conducted exploratory and confirmatory factor analyses on diagnostic interview data from a representative US population-based sample of 34 653 civilian, non-institutionalized individuals aged ≥18 years. We modeled the structure of lifetime DSM-IV diagnoses of BPD and antisocial personality disorder (ASPD), major depressive disorder, dysthymic disorder, panic disorder with agoraphobia, social phobia, specific phobia, generalized anxiety disorder, post-traumatic stress disorder, alcohol dependence, nicotine dependence, marijuana dependence, and any other drug dependence. RESULTS In both women and men, the internalizing-externalizing structure of common mental disorders captured the co-morbidity among all disorders including BPD. Although BPD was unidimensional in terms of its symptoms, BPD as a disorder showed associations with both the distress subfactor of the internalizing dimension and the externalizing dimension. CONCLUSIONS The complex patterns of co-morbidity observed with BPD represent connections to other disorders at the level of latent internalizing and externalizing dimensions. BPD is meaningfully connected with liabilities shared with common mental disorders, and these liability dimensions provide a beneficial focus for understanding the co-morbidity, etiology and treatment of BPD.

Personality in DSM-5: Helping delineate personality disorder content and framing the metastructure

The transition from the Diagnostic and Statistical Model of Mental Disorders (4th ed., text revision [DSM–IV–TR]; American Psychiatric Association, 2000) to the fifth edition (DSM–5) represents an unprecedented opportunity to integrate dimensional personality trait models into the official nosology. Not surprisingly, a variety of issues have arisen in contemplating this challenging integration. In this article, we address how a dimensional personality trait model could be a helpful component of DSM–5, from the perspective of our roles as work group members and advisors involved in the creation of a trait model and corresponding assessment instrument. We focus in particular on two potential roles for a trait model in DSM–5 that are under official consideration. First, a dimensional personality trait model might be helpful in delineating the content of personality disorders. Second, a trait model might assist in organizing the “metastructure” of DSM–5 (i.e., the arrangement of chapters and other broader classificatory rubrics).

The Structure and Predictive Validity of the Internalizing Disorders

Multivariate comorbidity research indicates mood and anxiety (internalizing) disorders share one or more common liabilities, but categorical, dimensional, and hybrid accounts of these liabilities have not been directly compared. We modeled seven internalizing disorders in a nationally representative sample of 43,093 individuals via confirmatory factor, latent class, exploratory factor mixture, and exploratory structural equation modeling analyses. A two-dimensional (distress-fear) liability structure fit best and replicated across gender, assessment waves, and lifetime/12-month diagnoses. These liabilities, not disorder-specific variation, predicted future internalizing pathology, suicide attempts, angina, and ulcer.

Contrasting prototypes and dimensions in the classification of personality pathology: evidence that dimensions, but not prototypes, are robust.

BACKGROUND DSM-5 may mark the shift from a categorical classification of personality pathology to a dimensional system. Although dimensional and categorical conceptualizations of personality pathology are often viewed as competing, it is possible to develop categories (prototypes) from combinations of dimensions. Robust prototypes could bridge dimensions and categories within a single classification system. METHOD To explore prototype structure and robustness, we used finite mixture modeling to identify empirically derived personality pathology prototypes within a large sample (n=8690) of individuals from four settings (clinical, college, community, and military), assessed using a dimensional measure of normal and abnormal personality traits, the Schedule for Nonadaptive and Adaptive Personality (SNAP). We then examined patterns of convergent and discriminant external validity for prototypes. Finally, we investigated the robustness of the dimensional structure of personality pathology. RESULTS The resulting prototypes were meaningful (externally valid) but non-robust (sample dependent). By contrast, factor analysis revealed that the dimensional structures underlying specific traits were highly robust across samples. CONCLUSIONS We interpret these results as further evidence of the fundamentally dimensional nature of an empirically based classification of personality pathology.

Transdiagnostic factors of psychopathology and substance use disorders: a review

PurposeResearch on the structure of mental disorders and comorbidity indicates that many forms of psychopathology and substance use disorders are manifestations of relatively few transdiagnostic latent factors. These factors have important consequences for mental disorder research and applied practice.MethodsWe provide an overview of the transdiagnostic factor literature, with particular focus on recent advances.ResultsInternalizing and externalizing transdiagnostic factors have been well characterized in terms of their structures, links with disorders, stability, and statistical properties (e.g., invariance and distributions). Research on additional transdiagnostic factors, such as thought disorder, is quickly advancing latent structural models, as are integrations of transdiagnostic constructs with personality traits. Genetically informed analyses continue to clarify the origins of transdiagnostic factor levels, and links between these factors and important environmental exposures provide promising new avenues of inquiry.ConclusionsTransdiagnostic factors account for the development and continuity of disorders and comorbidity over time, function as the primary links between disorders and important outcomes such as suicide, mediate associations between environmental exposures and disorders, provide an empirically supported classification system, and serve as foci for efficient, broadband intervention approaches. Overall, transdiagnostic factor research indicates the paramount importance of understanding these constructs and, thereby, broadening our understanding of mental disorder in general.